JPH07133435A - Biodegradable plastic molding - Google Patents

Abstract

PURPOSE:To produce the plastic molding having a practical strength and a practical durability and useful, e.g. for volume reduction of wastes by kneading a biodegradable plastic material, a biodegradable additive and another additive composed of a natural substance and molding the resultant kneaded material. CONSTITUTION:This plastic molding is produced by kneading or melt-blending (A) a biodegradable plastic material (preferably a polyester produced by a microorganism, an aliphatic polyester, a modified starch, etc.) with (B) an additive selected from a biodegradable additive (preferably a vegetable oil, collagen, an extreme thermophile, etc.) and another additive (preferably carbon fiber, glass fiber, etc.) composed of a natural substance and molding the resultant kneaded material. In addition, at least, a biopolymer which is a biodegradable additive is preferably used as the component (B).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biodegradable plastic molded product and a method for recovering resources, and more particularly to a biodegradable plastic molded product and a method for recovering resources which are practically used as durable materials.

[0002]

2. Description of the Related Art At present, biodegradable plastics that are completely decomposed and digested by microorganisms in soil are attracting attention as interest in the global environment increases. Several patent applications have already been filed regarding molded articles using such plastics (Japanese Patent Laid-Open No. 3-290461).
Japanese Patent Laid-Open No. 4-146952 and Japanese Patent Laid-Open No. 4-3
25526, etc.). These molded products are particularly used as films and packaging materials, and durability is not required.

[0003]

However, it is expected that in the near future it will be obligatory to collect products for durable materials such as electric products and computers, and research and development of decomposable materials used for housings and the like have been conducted. ing. As such a material, biodegradable plastics are considered to be advantageous since the recovered molded products can be decomposed at low cost. Further, to use it as a durable material, it is necessary to have strength and durability. At present, there is no known biodegradable plastic for use as a durable material that has both degradability, strength and durability.

In the electric circuit board used for electronic equipment, thermosetting resin is used in most cases except for inorganic materials such as ceramics, and wiring is formed on the surface of the board. Thermosetting resins are extremely difficult to melt, dissolve, etc., and a complicated process is required to separate and collect wiring metals. Further, since the thermosetting resin of the electric circuit board does not have decomposability, it remains semipermanently in the place where it is buried and disposed.

Further, from the viewpoint of resource saving, it is desired not only to decompose but also to recover the material.
The present invention has been made in view of the problems of the prior art, and an object of the present invention is to provide a biodegradable plastic molded product having strength and durability and a method for recovering resources.

[0006]

In order to solve the above problems, the present invention provides a biodegradable plastic material and at least one of a biodegradable additive and an additive consisting of a substance existing in nature. Provided is a biodegradable plastic molded product formed by using the kneaded product obtained by kneading or melting and mixing.

Particularly, the kneaded product preferably contains a biopolymer which is an additive having biodegradability. The biopolymer may be a vegetable oil, collagen or an extreme thermophile or a hyperthermophile. Further, the kneaded product preferably contains a fiber or fine particle substance made of at least one of carbon, silicon oxide and silicon dioxide as an additive made of a substance existing in nature. Alternatively,
The kneaded product may contain at least one of magnesium hydroxide and aluminum hydroxide as an additive made of a substance existing in nature.

The biodegradable plastic material is at least one selected from microorganism-produced polyester, aliphatic polyester, polyvinyl alcohol, polycaprolactone, polyhydroxyalkanoate, modified starch, natural polymer and polyisocyanate. preferable. The biodegradable plastic molded product can be molded by molding the kneaded product into a film, extrusion molding, or injection molding. The biodegradable plastic molded product may be, for example, a flat plate-shaped electric circuit board on which wiring is formed.

Further, according to the present invention, there is provided a method for recovering a resource, characterized in that the biodegradable plastic molded product as described above is decomposed by a microorganism and the biodegradable plastic material accumulated in the microorganism is recovered. Provided.

[0010]

The present inventors have found a biodegradable plastic that can be applied to a durable material having improved strength and durability by mixing various biodegradable plastic materials with a biodegradable additive. Is. Further, various biodegradable plastic materials were mixed with a substance existing in a large amount in nature, for example, an additive containing at least one of carbon, silicon oxide and silicon dioxide to improve strength and durability. We have found a biodegradable plastic that can be applied to durable materials.

Examples of such biodegradable plastic materials include polyesters produced by microorganisms, aliphatic polyesters, polyvinyl alcohol, polycaprolactone, polyhydroxyalkanoates, modified starches, natural polymers or polyisocyanates. On the other hand, the additive has a function as a plasticizer, a filler, a flame retardant, or the like depending on the type of substance, and a biodegradable biopolymer is used as one of the additives. Such biopolymers include vegetable oils, collagen or highly thermophilic or ultra-high thermophilic bacteria. These can be decomposed by microorganisms.

Further, as the other additive, a substance made of a substance existing in nature, for example, a substance made of carbon, silicon oxide or silicon dioxide and processed into a fibrous or fine particle may be used. In particular, it is preferable to mix magnesium hydroxide or aluminum hydroxide as an inorganic flame retardant in a plastic used for an electric circuit board which becomes hot. It should be noted that the substances existing in nature mixed as additives are not biodegradable, but only the naturally occurring components remain after the plastic is decomposed, so that adverse effects on the natural environment can be minimized.

A biodegradable plastic kneaded product obtained by mixing the above-mentioned biodegradable plastic material and additives, for example,
As a result of testing the strength of a molded article formed by extrusion molding or injection molding, a tensile strength and Izod impact value equivalent to or higher than those of polypropylene and ABS resin were obtained. Also, unlike polypropylene and ABS resin, it was decomposed in about one year by burying it in soil.

As described above, the biodegradable plastic molded product of the present invention has biodegradability and has sufficient strength and durability required for use as a durable material such as electric appliances and computer casings. . Further, the above-mentioned biodegradable plastic is decomposed and disappears in a culture solution containing microorganisms or in soil. As a result, the volume of waste can be reduced and the wiring metal of the electric circuit board can be recovered. In addition, it can be recycled by extracting the plastic material accumulated in the microorganisms.

According to the present invention, there is also provided an injection molded article of a microbial degradable resin containing the microbial degradable resin and a substance having antibacterial properties. In recent years, biodegradable resins have been increasingly applied due to the growing concern about global environmental problems. A biodegradable resin is a resin that has the property of assimilating and degrading certain microorganisms.Unlike ordinary general-purpose resins, it decomposes and disappears when left in the natural environment, leaving no adverse effect on the natural environment. Therefore, it is currently receiving much attention as a resin for injection molding. However, this resin has a problem that it is inferior in long-term durability in a natural environment or an environment similar thereto because of its biodegradability, and according to the injection-molded article of the present invention, such a problem is caused. The point can be solved.

There are many kinds of useful antibacterial agents depending on their action on microorganisms, but the following six kinds can be roughly classified. Inhibitors of cell wall peptide glucan biosynthesis β-lactam compounds such as penicillin and cephalosporins Inhibitors of microbial protein biosynthesis Puromycin, tetracycline, chloramphenicol, erythromycin, streptomycin, etc. Inhibitors of synthesis Azeserine, acridine, actinomycin D, battomycin, rifamycin, etc. Altering ion permeability of cell membranes Parinomycin, gramicidin A, nonactin, monensin, etc. , Quaternary ammonium salts such as benzalkonium chloride, biguanide compounds such as chlorhexidine, cyclic peptides such as tyrosidine, gramicidin S and polymyxin Group Ions Silver Ions and Complex Compounds Thereof Incorporation of one or more of these substances into a resin in a relatively small amount causes the substance to chemically decompose and inactivate, or moisture present in the environment. Biodegradability can be suppressed for a certain period of time until it flows out due to such reasons. The same effect can be obtained by mixing a substance in which any one of these substances is chemically bonded to the polymer chain.

Since each substance has different properties such as antibacterial property, chemical stability, and solubility in water, it is technically important to sufficiently consider the amount mixed in the resin. . At the same time, considering the economic effect,
Antibacterial substances of 0.01 and 100ppm
And the amount of the substance is 0.01 to the resin.
It is particularly preferred to use in an amount of ˜5% by weight.

The compounding is generally carried out by adding it at the time of kneading the resin in the same manner as mixing other additives and fillers with the resin. However, in order to suppress the decomposition of the antibacterial substance, it is desirable to carry out the kneading at the lowest temperature possible and in a short time. Under these conditions, it may be difficult to uniformly mix, but it is effective to prepare a masterbatch in advance, especially when a very small amount is mixed. Further, the above-mentioned silver ions are easily decomposed by ultraviolet rays and react with chlorine ions contained in tap water or the like to become silver chloride, which is easily deactivated. Therefore, it was absorbed in a fine powder of a silica gel carrier. There is also a method of using things.

According to the present invention, an alkali or acid component in an amount effective for neutralizing the acid or alkaline component contained in the polymer material having an ester bond in the polymer main chain is further added and mixed. This provides a method of modifying a resin that includes maintaining the resin substantially neutral. The present invention also provides a resin composition containing a polymer material having an ester bond in the polymer main chain, and an amount of an alkali or acid component effective to neutralize an acid or alkaline component contained in the polymer material. An article and a resin molded article comprising such a resin composition are provided.

In recent years, application of polymer materials having ester bonds (so-called polyester resins) has been advanced. The polyester resins are roughly classified into two types, thermosetting resins and thermoplastics. The present invention is effective for any of these, but is particularly effective for the latter. Thermoplastic polyester resin is polyethylene terephthalate (PE
T) and the like, which include a benzene ring in the molecular chain, so-called aromatic ones, and those consisting entirely of aliphatic hydrocarbons, the latter having a property of being decomposed by microorganisms, that is, a biodegradable resin, For example, poly 3-hydroxybutyrate, poly 3-hydroxyvaleate and the like are included.

Since all the resins have an ester bond, the synthesis is relatively easy. This is because, because it is chemically synthesized usually by polycondensation of dicarboxylic acid and glycol, various resins can be relatively easily synthesized under similar synthetic conditions by selecting and combining these substances. . On the other hand, this point is also a drawback of this type of resin. That is, when this type of resin is used for a long period of time or under chemically severe conditions, a small part of the ester bond is hydrolyzed to break the polymer chain, which causes deterioration of material physical properties. There was a problem.
Another study shows that if the main chain is cleaved, it is important to control this reaction because even if the cleaved part is very small, it has a great influence on the deterioration of material properties such as strength. Is.

The present inventors have found the following as a result of studying the mechanism of hydrolysis in order to reduce such problems. The resin often contains a small amount of an acidic or basic (alkaline) substance due to impurities contained in the raw material during the synthesis of the resin or the pH environment during the synthesis. In general, hydrolysis is greatly accelerated by acids or bases (alkalis). Therefore, it has been revealed that these components contained in the resin accelerate the reaction of the polymer chain cleavage (transesterification) of the resin, particularly when the material is placed in a wet environment. In order to suppress this reaction, the present inventors can improve the durability of the resin by quantifying these components contained in the resin and reducing their acid or alkali content by a neutralization reaction. The inventors of the present invention found out the above and arrived at the present invention.
At this time, it is desirable that the alkali or acid to be added be made into a fine powder in advance and sufficiently kneaded.

[0023]

EXAMPLES The present invention will be further described below with reference to examples. Example 1 Biodegradable Plastic Molded Product A biodegradable plastic material that is decomposed by microorganisms in soil is a polyester-based copolymer (PHBV) consisting of hydroxyvaleate (HV) and hydroxybutyrate (HB). A copolymerization ratio of 5:95 is used. To this powder, a fatty acid ester is mixed as a plasticizer, and a carbon fiber or glass fiber having a cross-sectional diameter of 0.3 to 1 μm and a length of 0.1 to 20 mm is mixed together as a filler (filler) for increasing the strength of the molded product. The obtained mixture is used as a plastic kneaded product. For comparison of the strength and the decomposition activity, three types were prepared by changing the mixing ratio of the plasticizer and the filler.

Table 1 shows the composition ratio of each plastic composition using carbon fiber.

[0025]

[Table 1]

Table 2 shows the composition ratio of each plastic composition using glass fiber.

[0027]

[Table 2]

Next, each of the above plastic compositions was melted and kneaded at a temperature of 165 ° C. in an injection molding machine, and then injected into a flat plate mold to obtain a standard tensile test piece (JIS K).
7113 dumbbell type) three types of plastic moldings are prepared. Next, a tensile test based on JIS K7113 was performed on each plastic molded product. For comparison, polypropylene and ABS
Similar tests were conducted on the resin.

The results are also shown in Tables 1 and 2. The tensile strength is indicated by the stress (unit: megapascal (MPa)) when the test piece breaks. According to this, the tensile strength increases both in the case of adding carbon fiber or glass fiber in proportion to the addition ratio of carbon fiber or glass fiber. Further, when the addition ratio of carbon fiber or glass fiber is the same, the tensile strength of glass fiber is higher than that of carbon fiber. Further, both of the above biodegradable plastics have higher tensile strength than polypropylene or ABS resin.

Then, the above test pieces were embedded in a soil (compost) composted with garbage produced at home, and the decomposition activity was measured for 6 months. The result is shown in FIG.
The horizontal axis represents elapsed time (monthly), and the vertical axis represents the remaining amount (%)
Represents In the figure, a symbol indicating the type of sample, for example,
PHBV80 / C19 is a copolymer (PHBV) 80
% Represents 19% of carbon (C) fiber and a molded product molded from the kneaded product. Other symbols have the same meaning. However, the symbol G represents glass fiber.

According to the results, the carbon fiber mixture decomposes faster as the carbon fiber mixing ratio decreases, and the carbon fiber mixing ratio 19% shows a residual amount of 60% after 6 months, and the mixing ratio 38%. % Showed a residual amount of 80% after 6 months. Also, the glass fiber mixture, like the carbon fiber mixture, decomposes faster as the glass fiber mixing ratio decreases, and the mixing ratio of 19% shows a residual amount of 65% after 6 months, The mixture of 38% showed a residual amount of 85% after 6 months. All of them show that they decompose steadily over time.

The biodegradability is similar to that without the addition of filler, and the carbon fiber remains in the soil after the decomposition and does not harm the ecosystem. Example 2 Biodegradable plastic molded product As a biodegradable plastic material, a copolymer (PHBV) having a copolymerization ratio of hydroxyvaleate (HV) and hydroxybutyrate (HB) of 5:95 is used. This powder was filled with a thermophile (Thermus thermophilis HB) that died as a filler.
The product to which 8) was added was used as a plastic kneaded product. For comparison of strength and degrading activity, three types were prepared by changing the mixing ratio of the extreme thermophile.

Table 3 shows the composition ratio of each plastic composition.

[0034]

[Table 3]

Next, each of the above-mentioned plastic compositions is melt-kneaded while being kept at a temperature of 165 ° C. in an injection molding machine, and then injected into a flat plate mold to form three types of plastic molded products having a flat plate shape of 8 × 100 × 100 mm. To create. Next, each plastic molded product was subjected to a tensile test based on JIS K7113 and an Izod impact test based on JIS K7110.

The results are also shown in Table 3. Here, the tensile strength is indicated by the stress (unit: megapascal (MPa)) when the test piece breaks. The Izod impact value is the energy (J /
m), the test piece is impacted with a mallet to break,
It is measured by the height at which the mallet bounces. According to the result,
The smaller the proportion of highly thermophilic bacteria added, the larger the tensile strength and Izod impact value. Polypropylene and ABS
It has almost the same value as resin, and has the strength required for durable materials.

Next, the above test pieces were embedded in the soil composted with the garbage produced at home, and the decomposition activity was measured for 6 months. The results are shown in Figure 2. In FIG. 2, the horizontal axis represents elapsed time (monthly unit), and the vertical axis represents remaining amount (%). In the figure, a symbol indicating the type of sample, for example, PH
BV90 / t10 represents a molded product molded from a kneaded product of a copolymer (PHBV) 90% and a highly thermophilic bacterium (t) 10%. Other symbols have the same meaning.

According to the results, the higher the mixing ratio of the extreme thermophile, the faster the decomposition, the mixture ratio of 30% shows a residual amount of 30% after 6 months, and the mixing ratio of 10% is 6%.
After months, it showed a residual amount of 35%. When extrapolated, all test pieces are expected to be completely decomposed approximately 10 months after burying. In addition, the decomposition rate was considerably faster than that of the plastic containing no extreme thermophile.

Example 3 Electric Circuit Board Next, a method for producing an electric circuit board made of a molded product of biodegradable plastic will be described. As the biodegradable plastic material, polyhydroxyalkanoate, polycaprolactone, modified starch, natural polymers such as chitin and chitosan, and polyisocyanate are used.

Further, due to the nature of the electric circuit board, a flame retardant is added in order to cope with the heat generation of the circuit. At this time, an inorganic flame retardant such as non-toxic magnesium hydroxide or aluminum hydroxide is used as a material that does not affect biodegradability and does not adversely affect organisms in the natural environment.
Since the workability is deteriorated when the addition amount of these is large, the addition amount is preferably 10 to 20% by weight.

Further, the above-mentioned biodegradable plastic material generally has a low softening point and therefore has a drawback that it does not have excellent dimensional characteristics when heated, but by adding 30 to 60% by weight of a fibrous substance as a reinforcing agent. The drawback is compensated. Glass fiber, carbon fiber,
Cellulose fibers, fibroin fibers and the like can be mentioned. Both of them are abundant in nature or are biopolymers, so that the effect on microorganisms can be minimized. From the viewpoint of reducing the volume of waste, cellulose fiber, fibroin fiber and the like are preferable.

The above biodegradable plastic material, flame retardant and reinforcing agent are mixed to prepare a biodegradable plastic kneaded product. This biodegradable plastic kneaded product is molded by extrusion molding, injection molding or film molding to prepare a flat substrate. Then, after forming a copper foil on this substrate, a circuit wiring is formed by photolithography, whereby an electric circuit substrate is produced.

Specific Example 1 As a biodegradable plastic material, a polyester-based copolymer of polyhydroxybutyric acid (hydroxybutyrate; HB) -polyhydroxyvaleric acid (hydroxyvalerate; HV) is used. In this case, considering the strength and processability of the molded product, it is preferable to contain polyhydroxyvaleric acid in an amount of 8 to 15% by weight. When the amount of polyhydroxyvaleric acid added is increased, the flexibility of the molded product is also increased, but from the viewpoint of processability, it is preferably 9 to 10% by weight.

To this material, 10 to 20% by weight of magnesium hydroxide powder is added as a flame retardant, and 20 to 40% by weight, preferably 30 to 40% by weight of cellulose fiber is added as a reinforcing agent. The aspect ratio (length / diameter ratio) of the cellulose fiber is appropriately in the range of 50 to 100. If it is too long, the surface of the molded product becomes rough, which is not preferable. Particularly, the range of 80 to 90 is preferable.

This kneaded material is injection molded to prepare a substrate. The injection molding conditions may be the same as those for polyethylene terephthalate (PET). After that, circuit wiring is formed on the substrate to prepare an electric circuit substrate. Table 4 shows the dielectric constant of this electric circuit board. Measurement is ASTM
According to D150.

[0046]

[Table 4]

According to this result, it can be seen that almost the same value can be obtained as compared with epoxy and ceramic. Example 2 Polycaprolactone is used as a biodegradable plastic material, and a mixture of chitin fibers (10 to 30% by weight) is used as a filler. Chitin fiber is a polysaccharide that is abundant in crustaceans and is rapidly degraded in nature.

This kneaded product is injection-molded to prepare a substrate, and then circuit wiring is formed on the substrate to prepare an electric circuit substrate. Table 4 also shows the dielectric constant of this electric circuit board. According to this result, it can be seen that almost the same value can be obtained as compared with epoxy and ceramic. Next, when the circuit board of Example 2 was embedded in the compost, as shown in FIG. 4, the remaining amount of plastic was about 30% in about 4 months, and 70% of the initial weight had disappeared. In this case, the copper used for the wiring could not be recovered due to oxidation.

Example 4 Resource Recovery Method Next, a method for recovering biodegradable plastic will be described. Here, the electric circuit board of Example 3 is used as an example of the molded product. After the above electric circuit board is prepared, microorganisms such as Pseudomonas
p. ), Alcaligenes s
p. ), Rhodospirillium
ium sp. ), Zoogloea s
p. ) And the like. This allows the plastic of the substrate to be completely decomposed.

At this time, the flame retardant, reinforcing agent, etc. contained in the plastic of the substrate settle at the bottom of the culture solution tank, and the metal parts remain without being decomposed, so that both can be easily recovered. it can. After completion of the decomposition treatment, the microorganisms in the culture solution are recovered. Then, it is dissolved in a solvent to extract the plastic accumulated in the microorganisms. New plastics can again be produced from this extract.

Even if it is discarded as a waste in the natural environment, after the plastic is decomposed, only the naturally occurring components remain, so that the adverse effect on the natural environment can be minimized. . Specific Example 3 The culture solution shown in Table 5 was placed in a culture solution tank, and the cells were Alcaligenes fe.
Acalis) was cultured, and the electric circuit board of Example 1 was immersed in this culture medium and left standing.

[0052]

[Table 5]

As shown in FIG. 3, when the plate thickness is 3 mm, 30
Almost all the plastic components decomposed and disappeared at 40 ° C for 40 days. After completion of the decomposition, the bacterial cells (microorganisms) were collected by centrifugation, dissolved in a solvent, and the polyhydroxybutyric acid / polyhydroxyvaleric acid copolymer accumulated in the bacterial cells was extracted. When the recovery rate was calculated, it was about 60%, which was good.

Further, the flame retardant, the strengthening agent, etc. settled at the bottom of the culture solution tank, and the metal parts remained without being decomposed, so that both could be easily recovered. Example 5 By copolymerizing 3-hydroxybutyrate (HB) and 3-hydroxyvaleate (HV), a resin having better mechanical properties can be obtained while maintaining biodegradability.

A masterbatch prepared by mixing 1.0% by weight of hexamethylene biguanide with a commercially available HB / HV copolymer ("Biopol S30" manufactured by Zeneca Corporation; HV ratio of about 5%, in pellet form) was prepared in advance. Was further added to the same resin in an amount of 10% by weight to prepare a resin composition. Care was taken to perform kneading in as short a time as possible in any process.

Using the resin composition obtained by this method, a plate-shaped test piece was prepared by an injection molding method, embedded in moist soil and left for 12 months (average temperature 20 ° C.), and periodically. When the test piece was taken out and the mechanical properties were measured, a large difference was observed in the change in mechanical strength, and the one mixed with the antibacterial agent showed a low degree of deterioration for a certain period of time, but the deterioration progressed thereafter. (Fig. 5).

Example 6 Since a molded product of a composition obtained by adding starch to a polyvinyl alcohol resin disintegrates in a natural environment, it can be regarded as a biodegradable resin in a broad sense. To this type of resin, "Matterby" of Nippon Synthetic Chemical Industry, fine silica gel powder (particle size: about 0.1 mm) in which silver nitrate was absorbed was added. An aqueous solution of silver nitrate (1.0%) was sprayed little by little onto a silica gel crushed to a particle size of 0.1 mm or less by a ball mill by spraying (100 g of silica gel with an aqueous solution of 10 m).
l), which was dried in the dark at 60 ° C. for 10 hours. The antibacterial composition thus prepared was kneaded into 1% by weight of Matterby. Using the resin composition prepared by this method, a plate-shaped test piece was prepared by an injection molding method, embedded in moist soil and left for 10 months (average temperature 20 ° C.),
When test pieces were taken out periodically and the weight change was measured, a large difference was observed in the degree of weight reduction (FIG. 6).

Example 7 Polycaprolactone (PCL) is a resin having biodegradability and capable of producing an injection-molded product having good mechanical properties. A masterbatch was prepared in advance, in which 1.0% by weight of trimethylphenylammonium chloride was blended with "Plaxel H-5" of commercially available PCL (manufactured by Daicel Chemical Industries Ltd.), and 1% by weight was further added to the same resin. A resin composition was prepared. Care was taken to perform kneading in the shortest possible time in all processes. In particular, we paid attention to the temperature control during melting of the resin and tried to process it at a relatively low temperature.

Using the resin composition obtained by this method, a plate-shaped test piece was prepared by injection molding, buried in moist soil and left for 12 months (average temperature 20 ° C.), and periodically. When the test piece was taken out and the mechanical properties were measured, a large difference was observed in the change in mechanical strength, and the one mixed with the antibacterial agent showed a low degree of deterioration for a certain period of time, but the deterioration progressed thereafter. (Fig. 7).

Example 8 By copolymerizing 3-hydroxybutyrate (HB) and 3-hydroxyvaleate (HV), a resin having better mechanical properties while maintaining biodegradability is obtained. You can A plate-shaped test piece was prepared from a commercially available HB / HV copolymer ("Biopol S30" manufactured by Zeneca Corporation; HV ratio of about 5%) by an injection molding method, and the test piece was placed in an environment of 70 ° C and 50% humidity for 2 minutes. When left for a month, the mechanical strength was remarkably reduced (FIGS. 8 and 9). The amount of water-soluble components (acid or alkali components) of this molded article was analyzed.

The analysis method is as follows. The resin pieces are finely crushed to a particle size of 0.5 mm or less, immersed in a small amount of warm ethanol, shaken for about 24 hours, and then filtered to isolate the solution. This solution is subjected to solvent extraction with a water-ether system to dissolve the water-soluble component in water, and this aqueous solution is titrated with a strong acid or a strong alkali to measure the amount of the acid or alkali component in the resin.

By this method, commercially available Biopol S3
It was confirmed that the acid component of 0.2 contained an acid component of 0.2 mmol per 100 g of the resin. Next, this resin was remelted by using a resin kneader, and 0.1 mmol (0.
2 millimolar equivalent) of sodium carbonate fine powder (particle size 0.0
(5 mm or less) was kneaded and thoroughly mixed. A test piece was prepared by injection molding using this resin, and the humidity was 70 ° C.
When left for 2 months in a 0% environment, the decrease in mechanical strength was not observed as much as the original resin (FIGS. 8 and 9).

Example 9 PET resin is widely used for beverage bottles and the like. This resin piece was finely crushed with a ball mill or the like to a particle size of 0.5 mm or less, and the water-soluble component was extracted in the same manner as in Example 8 to measure the amount of the acid or alkali component in the resin.
It was found that the acid component was contained in an amount of 0.026 mmol per 100 g of the resin.

Next, this resin was remelted using a resin kneader, and 0.026 mmol of potassium carbonate fine powder (particle size: 0.05 mm or less) per 100 g was kneaded and sufficiently mixed. When a test piece was prepared by injection molding using this resin and left for 2 months in an environment of 70 ° C. and 50% humidity, the mechanical strength was higher than that after the original resin was similarly tested. Only a small decrease (Figs. 10 and 1)
1).

Example 10 A thermosetting polyester resin, which is composited with glass fiber and reinforced, is widely used in bathtubs, boats, skis and the like. Commercially available resin pieces (reinforced with 35% by weight of glass fiber) were finely crushed with a ball mill or the like to a particle size of 0.5 mm or less, and water-soluble components were extracted in the same manner as in Example 1 to remove acid or As a result of measuring the amount of the alkaline component, the alkaline component is 0.055 mmol per 100 g of the resin.
I found it included.

Next, this resin was remelted using a resin kneader, and 0.0275 mmol (0.055 mmol equivalent) of ammonium nitrate fine powder (particle size 0.05
mm or less) and kneaded thoroughly. Using this resin, a test piece was prepared by a hand lay-up method, and 10
When immersed in boiling water at 0 ° C. and left for 10 days, the mechanical strength was reduced to a lesser extent than after the original resin was similarly tested.

[0067]

As described above, the biodegradable plastic molded article of the present invention has biodegradability and
It has sufficient strength and durability required for durable materials such as electric appliances and computer casings. It should be noted that the substances existing in nature mixed as additives are not biodegraded, but only the naturally occurring components remain after the plastic is decomposed, so that adverse effects on the natural environment can be minimized. Further, this biodegradable plastic molded product decomposes and disappears in a culture solution containing microorganisms or in soil. As a result, the volume of waste can be reduced and the wiring metal of the electric circuit board can be recovered. In addition, it can be recycled by extracting the plastic material accumulated in the microorganisms.

Further, according to the present invention, it is possible to provide a durable biodegradable resin injection molded product or polyester resin molded product.

[Brief description of drawings]

FIG. 1 is a diagram showing the degradability of a biodegradable plastic molded article according to an example of the present invention in soil.

FIG. 2 is a diagram showing the degradability of a biodegradable plastic molded article according to an example of the present invention in soil.

FIG. 3 is a diagram showing the degradability of a biodegradable plastic molded article according to an example of the present invention in a culture solution.

FIG. 4 is a diagram showing the degradability of a biodegradable plastic molded article according to an example of the present invention in soil.

FIG. 5 is a diagram showing the degradability of injection-molded articles according to Examples and Comparative Examples of the present invention in soil.

FIG. 6 is a diagram showing the degradability of injection-molded articles according to Examples and Comparative Examples of the present invention in soil.

FIG. 7 is a diagram showing the degradability of injection-molded articles according to Examples and Comparative Examples of the present invention in soil.

FIG. 8 is a diagram showing the decomposability of injection-molded articles according to Examples and Comparative Examples of the present invention under a high temperature and high humidity environment.

FIG. 9 is a diagram showing the decomposability of injection-molded articles according to Examples and Comparative Examples of the present invention under a high temperature and high humidity environment.

FIG. 10 is a diagram showing decomposability of injection-molded articles according to Examples and Comparative Examples of the present invention in a high temperature and high humidity environment.

FIG. 11 is a diagram showing the decomposability of injection-molded articles according to Examples and Comparative Examples of the present invention under a high temperature and high humidity environment.

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Takaharu Asano 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Limited

Claims (20)

[Claims] 1. By kneading a biodegradable plastic material and at least one of a biodegradable additive and an additive consisting of a substance existing in nature,
Alternatively, a biodegradable plastic molded product formed by using a kneaded product obtained by melting and mixing. 2. The biodegradable plastic molded product according to claim 1, wherein the kneaded product contains a biopolymer which is an additive having biodegradability. 3. The biopolymer is vegetable oil, collagen, or an extremely thermophilic bacterium or an extremely thermophilic bacterium.
The biodegradable plastic molding described. 4. The raw material according to claim 1, wherein the kneaded product contains a fiber or a particulate substance made of at least one of carbon, silicon oxide and silicon dioxide, which is an additive made of a substance existing in nature. Degradable plastic molding. 5. The biodegradable plastic molded product according to claim 1, wherein the kneaded product contains at least one of magnesium hydroxide and aluminum hydroxide, which is an additive made of a substance existing in nature. 6. The biodegradable plastic material is at least one selected from microorganism-produced polyester, aliphatic polyester, polyvinyl alcohol, polycaprolactone, polyhydroxyalkanoate, modified starch, natural polymer and polyisocyanate. The biodegradable plastic molded product according to claim 1. 7. The biodegradable plastic molded product according to claim 1, which is molded by film-forming the kneaded product, extrusion-molding or injection-molding. 8. The biodegradable plastic molded product according to any one of claims 1 to 7, which is a flat electric circuit board having wiring formed on the surface thereof. 9. A resource recovery characterized by decomposing the biodegradable plastic molding according to claim 1 with a microorganism and recovering the biodegradable plastic material accumulated in the microorganism. Method. 10. An injection-molded product of a microbial-degradable resin containing a microbial-degradable resin and a substance having antibacterial properties. 11. An aliphatic polyester, polycaprolactone, polyvinyl alcohol, starch-based polymer, chitin, which is synthesized by a microbial biodegradable resin by a biochemical process by a microorganism or by polycondensation of an aliphatic diol and an aliphatic dicarboxylic acid. The injection-molded product according to claim 10, containing at least one selected from the group consisting of chitosan-based polymers, polyamino acids, collagen, cellulose, lignin, polyurethane-based polymers and polyether-based polymers. 12. The antibacterial substance is a β-lactam compound, puromycin, tetracycline, chloramphenicol, erythromycin, streptomycin, azeserine, acridine, actinomycin D, butomycin, rifamycin, palinomycin, gramicidin A, nonactin, monensin. Selected from the group consisting of compounds such as ionophores, chlorocresols, phenols such as xylol, quaternary ammonium salts such as benzalkonium chloride, piguanide compounds, tyrosidine, gramicidin S, cyclic peptides such as polymyxin, and compounds containing silver ions. The injection-molded article according to claim 10, containing at least one kind. 13. The injection-molded article according to claim 10, wherein the antibacterial substance is chemically bound to the polymer compound or physically adsorbed or attached thereto. 14. A resin is substantially prepared by adding and mixing an amount of alkali or acid component effective for neutralizing an acid or alkaline component contained in a polymer material having an ester bond in the polymer main chain. A method for modifying a resin, the method including maintaining the neutrality. 15. The method according to claim 14, wherein the polymer material is a thermoplastic resin or a thermosetting resin containing an aromatic or aliphatic hydrocarbon in the main chain. 16. The method according to claim 14, wherein the polymer material is poly-3-hydroxybutyrate, 3-hydroxyvalerate or a copolymer thereof. 17. A resin composition comprising a polymer material having an ester bond in the polymer main chain and an amount of an alkali or acid component effective for neutralizing an acid or alkaline component contained in the polymer material. . 18. The composition according to claim 17, wherein the polymer material is a thermoplastic resin or a thermosetting resin containing an aromatic or aliphatic hydrocarbon in the main chain. 19. The composition according to claim 17, wherein the polymer material is poly-3-hydroxybutyrate, poly-3-hydroxyvaleate or a copolymer thereof. 20. A resin molded product comprising the resin composition according to claim 17.